A clinical resource core will be created to support the four projects. Serum, tissue, and clinical fungal isolates will be prospectively collected from a diverse group of patients with different types of Candida and Aspergillus infections. These specimens will be stored, characterized with clinical data, and a database for retrieval will be created for use by investigators of the four projects to characterize determinants of fungal virulence that are turned on in the course of various types of infection and pertinent host responses. Specimens will be made available to outside investigators to complement the program's objectives. Administrative support to the program project will also be provided.